Method and material for forming a double exposure lithography pattern

ABSTRACT

A method of lithography patterning includes forming a first material layer on a substrate; forming a first patterned resist layer including at least one opening therein on the first material layer; forming a second material layer on the first patterned resist layer and the first material layer; forming a second patterned resist layer including at least one opening therein on the second material layer; and etching the first and second material layers uncovered by the first and second patterned resist layers.

CROSS-REFERENCE

This application claims priority from U.S. Provisional PatentApplication Ser. No. 60/821,605 filed on Aug. 7, 2006, entitled “METHODAND MATERIAL FOR FORMING A DOUBLE EXPOSURE LITHOGRAPHY PATTERN”. Thepresent disclosure is related to the following commonly-assigned U.S.patent applications, the entire disclosures of which are herebyincorporated herein by reference: U.S. Ser. No. 60/708,208 filed Aug.15, 2005 by inventors Ching-Yu Chang, Chin-Hsiang Lin, and Burn Jeng Linfor “METHOD FOR FORMING A LITHOGRAPHY PATTERN”; and U.S. Ser. No.11/426,233 filed Jun. 23, 2006 by inventors Ching-Yu Chang, Chin-HsiangLin, and Burn Jeng Lin for “METHOD FOR FORMING A LITHOGRAPHY PATTERN”.

BACKGROUND

Semiconductor technologies are continually progressing to smallerfeature sizes, for example down to feature sizes of 65 nanometers, 45nanometers, and below. A patterned photoresist (resist) layer used toproduce such small feature sizes typically has a high aspect ratio.Maintaining a desired critical dimension (CD) can be very difficult forvarious reasons. For example, a resist layer may experience patterncollapse and CD degradation during a lithography patterning process.When double patterning techniques are utilized, additional issues may bebrought out, such as profile scum, high manufacturing cost, and roundcorners.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read in association with the accompanyingfigures. It is noted that, in accordance with the standard practice inthe industry, various features in the drawings are not drawn to scale.In fact, the dimensions of illustrated features may be arbitrarilyincreased or decreased for clarity of discussion.

FIGS. 1 through 7 are sectional views of one embodiment of a deviceduring various fabrication stages thereof.

FIGS. 8 a through 13 a and FIGS. 8 b through 13 b are top views andsectional views, respectively, of another embodiment of a device duringvarious fabrication stages.

FIGS. 14 a through 19 a and FIGS. 14 b through 19 b are top views andsectional views, respectively, of yet another embodiment of a deviceduring various fabrication stages.

FIG. 20 is a schematic view of a top layer utilized in the embodiment ofFIGS. 1 through 7.

FIGS. 21 a and 21 b are schematic views showing different embodiments ofpart of the top layer of FIG. 20.

FIG. 22 is a flowchart showing one embodiment of a method of lithographypatterning.

FIGS. 23 through 34 are sectional views of another embodiment of adevice during various fabrication stages.

FIG. 35 is a flowchart showing another embodiment of a method oflithography patterning.

DETAILED DESCRIPTION

It is understood that the following disclosure provides many differentembodiments, or examples, for implementing different features of variousembodiments. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Forexample, the formation of a first feature over or on a second feature inthe description that follows may include embodiments in which the firstand second features are formed in direct contact, and may also includeembodiments in which additional features may be formed between the firstand second features, such that the first and second features may not bein direct contact. In addition, the present disclosure may repeatreference numerals and/or letters in the various examples. Thisrepetition is for the purpose of simplicity and clarity and does not initself dictate a relationship between the various embodiments and/orconfigurations discussed.

FIGS. 1-7 are sectional views showing one embodiment of a device 100during various fabrication stages. With reference to FIGS. 1-7, a methodfor lithography patterning is described.

FIG. 1 shows a semiconductor device 100 having a silicon substrate 110.The substrate 110 may alternatively be made of some other suitablesemiconductor material, including Ge, SiGe, or GaAs. Further, thesubstrate 110 may alternatively be made of some other suitableelementary semiconductor such as diamond; a suitable compoundsemiconductor such as silicon carbide, indium arsenide, or indiumphosphide; or a suitable alloy semiconductor such as silicon germaniumcarbide, gallium arsenic phosphide, or gallium indium phosphide. Thesubstrate 110 may include various doped regions, dielectric features,and multilevel interconnects. The substrate 110 may alternatively be anon-semiconductor material such as a glass substrate forthin-film-transistor liquid crystal display (TFT-LCD) devices, or fusedquartz or calcium fluoride for a photomask (mask or reticle). Thesubstrate 110 may include a layer to be patterned such as a dielectriclayer, a semiconductor layer, or a poly-silicon layer.

An underlying material layer (also referred to as an “under-material”layer or simply “material” layer) 120 is formed on the substrate 110.The material layer 120 may function as a hard mask and/or a bottomanti-reflective coating (BARC). The material layer has a thicknessranging between about 50 angstroms and 9000 angstroms in one embodiment.For example, the thickness of the under-material layer 120 can be about500 angstroms. In another embodiment, the material layer 120 has athickness ranging between about 1000 angstroms and 3500 angstroms.Further, the material layer 120 may have other parameters that fallwithin selected ranges. For example, the material layer 120 has arefractive index in a range between about 1 and 3, and an extinctioncoefficient (absorption value) κ in a range between about 0.01 and 1.0.Alternatively, the material layer 120 may have a refractive index ofabout 1.75 and an extinction coefficient of about 0.5.

In the present embodiment, the material layer 120 includes an organicpolymer. The material layer 120 may be substantially free of siliconand/or substantially free of hydroxyl groups and carboxyl groups. Thematerial layer 120 may include a photoresist (or resist) that is eithera positive-type or negative-type, with or without photosensitivematerial. The material layer 120 may include a proper BARC material andmay further have a top layer to cover the BARC material. The top layermay be about 50 angstroms thick, and substantially free of hydroxylgroups and carboxyl groups. The material layer 120 may includeconventional polymer material or resist material. For example, thematerial layer may be one of t-Butyloxycarbonyl (t-BOC) resist, acetalresist, and environmentally stabilized chemically amplified photoresist(ESCAP) that are known in the art. For the material layer 120 made ofpolymeric material, the polymeric material may be cross-linked. Forexample, the polymeric material can be spin-on coated to the substrate110 and then cross-linked using a baking process with temperatureranging between about 90° C. and 300° C. Alternatively, this temperaturerange could be about 100° C. to 180° C. Alternatively, the polymericmaterial may not be cross-linked, and in that case the material layer120 may use a solvent that is not capable of dissolving a resist layeror not dissolved by the resist layer formed above the material layer120. For example, the material layer 120 may use butanol as a solvent.

Alternatively, the material layer 120 may use other suitable materialsthat are different from a protective layer that is to be formed abovethe material layer 120 to protect a resist pattern on the material layer120. For example, the material layer 120 may include silicon nitride orsilicon oxynitride in order to be different from a protective layercontaining silicon oxide, in which the two layers have substantiallydifferent etching rates during an etching process.

A middle layer 130 is formed on the material layer 120. The middle layer130 includes a silicon-containing organic polymer, which may use asolvent different from that of the resist layer. The solvent of themiddle layer is not capable of dissolving a resist layer. For example,the middle layer can use butanol, isobutanol, isopentanol and/or IPA asa solvent. The polymeric material may be cross-linked. The middle layer130 may include a silicon-containing inorganic polymer. For example, theinorganic polymeric material may include silicon oxide. The middle layermay include a metal-containing organic polymer material that containsmetal such as titanium, titanium nitride, aluminum, and tantalum. Inanother embodiment, the middle layer 130 may include silicon nitride orsilicon oxynitride. The middle layer 130 may include pure silicon suchas polycrystalline silicon or silicon oxide. For example, the middlelayer 130 may include spin-on glass (SOG) known in the art. The middlelayer 130 may be thermally baked for cross-linking, thus without furtherrequiring the solvent. The middle layer 130 may have a thickness rangingbetween about 500 and 2000 angstroms, or alternatively a range betweenabout 800 and 900 angstroms.

A patterned resist layer 140 is then formed on the middle layer 130.Resist layer 140 includes a plurality of openings, such that portions ofthe middle layer 130 are uncovered within the openings. The openings ofthe resist layer 140 are configured according to a predeterminedpattern. The resist layer 140 may have a thickness ranging between about50 angstroms and 5000 angstroms. Alternatively, the resist layer 140 mayhave a thickness ranging between about 500 angstroms and 3000 angstroms,or ranging between about 1000 angstroms and 1500 angstroms. The resistlayer 140 can be a positive-type resist or a negative-type resist. Foradvanced semiconductor patterning using an extreme ultraviolet (EUV)radiation beam, the resist layer 140 may use a chemical amplification(CA) resist. The patterned resist layer 140 is formed by a lithographyprocess that may include processing steps of resist coating, softbaking, mask aligning, exposing, post-exposure baking, developing, andhard baking. For illustration, the exposing process may be carried outby exposing the semiconductor device 100 under a radiation beam througha mask having a predefined pattern (or a reversed pattern). Theradiation beam may be ultraviolet (UV) or EUV, such as a 248 nm beamfrom a Krypton Fluoride (KrF) excimer laser, or a 193 nm beam from anArgon Fluoride (ArF) excimer laser. The lithography process may utilizeother exposing modes or technologies, such as on-axis, off-axis,quadripole, or dipole exposure technologies. The lithography patterningmay alternatively be implemented or replaced by other proper methodssuch as maskless lithography, electron-beam writing, ion-beam writing,and molecular imprint techniques. The patterned resist layer 140 mayinclude acid molecular or radiation-sensitive acid generator, such thatacid can be generated when a radiation beam is applied.

The patterned resist layer 140 may be further processed using ahardening process. The hardening process may include plasma treatment,ultraviolet (UV) curing, ion implant bombard, e-beam treatment, orcombinations thereof.

Referring to FIG. 2, a top layer 150 is formed on the patterned resistlayer 140 and in the openings thereof. The top layer substantially fillsthe openings in the patterned resist layer 140. The top layer 150substantially covers portions of the middle layer 130 that are exposedwithin the openings in the patterned resist layer 140. The top layer 150may include a silicon-containing organic polymer, which may use asolvent different from that of the resist layer. The solvent of the toplayer is not capable of dissolving the resist layer 140. The top layermay utilize an alcohol based solvent. For example, the top layer can usebutanol, isobutanol, isopentanol and/or IPA as a solvent. The polymericmaterial may be cross-linked. The top layer 150 may include asilicon-containing inorganic polymer. For example, the inorganicpolymeric material may include silicon oxide. The top layer mayalternatively include a metal-containing organic polymer material thatcontains metal such as titanium, titanium nitride, aluminum, andtantalum. The metal-containing material used for the top layer mayinclude Ti, TiN, Al, AlOx, W, WSi, or WOx. In another embodiment, thetop layer 150 may include silicon nitride or silicon oxynitride. The toplayer 150 may include pure silicon such as polycrystalline silicon orsilicon oxide. For example, the top layer 150 may include spin-on glass(SOG) known in the art.

Referring to FIG. 3, another patterned resist layer 160 is then formedon the top layer 150. Resist layer 160 includes a plurality of openings,such that portions of the top layer 150 are exposed within the openings.The patterned resist layer 160 may be substantially similar to theresist layer 140 discussed above, in terms of function, formation, andcomposition. The openings in the patterned resist layer 160 may beconfigured relative to the openings of the patterned resist layer 140 sothat a double patterning technique can be utilized. For example, theopenings in the patterned resist layers 140 and 160 may be configured toachieve pitch splitting. In another example, the openings in thepatterned resist layers 140 and 160 may be configured to form variouscontact holes.

Referring to FIG. 4, an etching process is applied to remove material ofthe middle layer 130 and the top layer 150 within the openings of thepatterned resist layers 140 and 160. The etch process may use a CF₄,C₃F₈, C₄F₈, CHF₃, CH₂F₂ dry etch or a buffered hydrofluoric acid (BHF)wet etch to etch silicon dioxide in various examples. Since both themiddle layer 140 and the top layer 160 may include a silicon-containingor a metal-containing material, it is possible to choose a properetchant that will concurrently remove material of both layers 130 and150, to expose portions of the material layer 120 located within theopenings of the patterned resist layers 140 and 160.

Referring to FIG. 5, an etching process is applied to the material layer120. The etching process is chosen so that the material layer 120 has ahigher etch rate than the middle layer 130 and the top layer 150. Inanother example, if the material layer 120 includes organic materialsuch as a resist material, oxygen may be chosen as the etchant in orderto remove the under layer 120 during a plasma etching. When the materiallayer 120 is similar to a resist material, the patterned resist layers140 and 160 may also be consumed during etching of the material layer120. The silicon material inside the middle and top layers 130 and 150may react under the oxygen plasma to form silicon oxide, which has ahigh etching resistance during the etching process. In another example,if the middle layer includes silicon oxide, the silicon oxide wouldprovide an etching resistance. In another example, if the middle and toplayers include titanium, titanium nitride, tantalum, aluminum, metalion, metal complex, organic metal, or a combination thereof, then metaloxide may be formed and provide an etching resistance. The etchingprocess may alternatively be implemented using a nitrogen plasma or amixture of oxygen, hydrogen, carbon fluoride, carbon bromide andnitrogen plasma, during which silicon-containing material in the middleand/or top layers will be transformed into an associated nitride oroxynitride.

Referring to FIG. 6, the substrate 110 is etched through the patternedmaterial layer 120 to form a plurality of trenches, using a suitableetching process including a dry etch or a wet etch. At least some of thematerial layer 120 may be consumed during the etching process. Theremainder of the material layer 120 is thereafter removed, asillustrated in FIG. 7.

The method described above with reference to FIGS. 1 to 7 provides adouble patterning process. This process achieves double exposure andsingle etch to the middle and top layers. This can reduce themanufacturing cost and minimize CD variation. The process may beutilized in various applications. In one example, a plurality of contactholes may be formed, as illustrated in various fabrication stages in thetop views of FIGS. 8 a to 13 a, and the corresponding sectional views ofFIGS. 8 b to 13 b. Alternatively, a plurality of line features withsplit pitch may be formed, as illustrated in various fabrication stagesin the top views of FIGS. 14 a to 19 a, and the corresponding sectionalviews of FIGS. 14 b to 19 b.

The top layer 150 used in the above-described process is furtherexplained in association with FIG. 20. The top layer 150 may have arefractive index ranging from about 1.1 to 1.9 and a absorption valueranging from about 0.001 to 0.8. In one example, the refractive index isabout 1.8, and the absorption value is about 0.2. The top layer may havea silicon content that is more than about 20% by weight. The top layermay also have a cure temperature that is less than about 150° C.

With reference to FIG. 20, the top layer 150 includes a first polymer152. The first polymer 152 further includes a functional unit ‘f”capable of enhancing etching resistance during an etching process. Thisfunctional unit may include a tertiary carbon structure, a double bond,a triple bond, or combinations thereof. The first polymer 152 alsoincludes a reaction unit ‘c’ that is capable of reacting to across-linker. The reaction unit ‘c’ may include a functional group suchas OH, COOH, anhydride, or combinations thereof. The first polymer 152may include a backbone unit such as those illustrated in FIGS. 21 a and21 b. The backbone units Si—O or Si—Si can be repeated and/or combined.In FIG. 21 a, R1 to R6 may each be hydrogen, a halide atom, a straightalkyl, a branched alkyl, a cyclic alkyl, a fluorinated alkyl group, asilicon oxide alkyl or a silicon alkyl of about 1 to 10000 atom unit. InFIG. 21 b, R1 to R6 may each be hydrogen, a fluorine atom, a straightalkyl, a branched alkyl, cyclic alkyl, a fluorinated alkyl group, asilicon oxide alkyl or a silicon alkyl of about 1 to 10000 atom unit.

Referring again to FIG. 20, the top layer 150 further includes across-linker 154 with various reaction units ‘d’ capable of reactingwith the first polymer 152 and other polymers if present. The reactionunit ‘d’ may include a functional group such as OH, COOH, anhydride, orcombinations thereof. The cross-linking temperature (cure temperature)ranges between about 100° C. and 250° C. The baking temperature may beabout 150° C., for example. The cross-linker 154 may includeN((CH2)xOH)y where the parameter ‘x’ has a range from 1 to 10 andparameter ‘y’ has a range from 1 to 4. Exemplary interactions betweenthe polymer and the cross-linker may include R1OCH3+R2OH->R1OR2+HOCH3 orR1OH+ R2OH->R1OR2+H2O.

Still referring to FIG. 20, the top layer 150 may include a secondpolymer 156. The second polymer 156 includes a functional unit ‘e’capable of absorbing imaging light during an etching process. Thefunctional unit may include a double bond, a triple bond, orcombinations thereof. For example, the functional unit includes a benzylgroup, phenyl group, or substitute benzyl group. The second polymer 156also includes a reaction unit ‘c’ capable of reacting to thecross-linker 154. The second polymer 156 includes a backbone unitsimilar to those illustrated in FIGS. 21 a and 21 b and described above.

FIG. 22 is a flowchart showing an embodiment of a method 200 oflithography patterning, which is the lithography patterning describedabove in association with FIGS. 1-7. The method 200 begins at step 202by forming an underlying material layer on a substrate, and thencontinues at step 204 by forming a middle layer on the under materiallayer. At step 206, a first patterned resist layer is formed on themiddle layer. At step 208, a top layer is formed on the first patternedresist layer, and at step 210 a second patterned resist layer is formedon the top layer. At step 212, the top and middle layers are etchedusing the first and second patterned resist layers as a mask. At step214, the underlying material layer is etched using the patterned top andmiddle layers as a mask. At step 216, the substrate is etched using theunderlying material layer as a hard mask. Various changes, substitutionsand alterations can be made in this method without departing from thespirit and scope of the present disclosure.

FIGS. 23 to 34 are sectional views showing a further device 300 atrespective different stages of fabrication, where the device 300 is analternative embodiment of the device 100 shown in FIGS. 1-7. In FIGS.23-34, a method for lithography patterning is disclosed. FIG. 23 showsthat the semiconductor device 300 includes a silicon substrate 310. Thesubstrate 310 may alternatively be made of some other suitable material,for example as described above in association with the substrate 110.

An underlying material layer 320 is formed on the substrate 310. Thematerial layer 320 is chosen so that it is substantially different froma hard mask layer subsequently formed above it in terms of etching rate.For example, the material layer 320 may be made of a materialsubstantially similar to that described above for the material layer120. The material layer 320 may alternatively include a multilayerstructure. For example, the material layer 320 may include a firstpolymer layer and a second polymer layer disposed on the first polymerlayer. The second polymer layer may include a radiation-sensitivematerial sensitive to the radiation beam of an exposure system such asan ultraviolet, extreme ultraviolet (EUV), or electron-beam system.

Referring to FIG. 24, a patterned resist layer 330 is formed on theunderlying material 320. The resist layer 330 has a plurality ofopenings, such that portions of the material layer 320 are exposedwithin the openings. The patterned resist layer 330 may be substantiallysimilar to the resist layer 130 described above, in terms of function,formation, configuration, and composition.

Referring to FIG. 25, a hard mask layer 340 is formed on the patternedresist layer 330, and in the openings thereof. The hard mask layersubstantially fills the openings of the patterned resist layer 330, andthus substantially covers the portions of the underlying material layer320 exposed within the openings of the patterned resist layer 330. Thehard mask layer 340 includes a silicon-containing organic polymer, whichmay use a solvent different from that of the resist layer. The solventof the hard mask layer is not capable of dissolving the resist layer330. The hard mask layer may use an alcohol based solvent. For example,the hard mask can use butanol, isobutanol, isopentanol and/or IPA as asolvent. In one example, the silicon-containing organic polymer mayinclude silsesquioxane (SSQ). The polymeric material may becross-linked. The hard mask layer 340 may include a silicon-containinginorganic polymer. For example, the inorganic polymeric material mayinclude silicon oxide. The hard mask layer may alternatively include ametal-containing organic polymer material that contains metal such astitanium, titanium nitride, aluminum, and tantalum. In anotherembodiment, the hard mask layer 340 may include silicon nitride orsilicon oxynitride. The hard mask layer 340 may include pure silicon,such as polycrystalline silicon or silicon oxide. The hard mask layer340 may include spin-on glass (SOG), known in the art. The hard masklayer 340 may be similar to the top layer 150 of FIG. 2 or FIG. 20.

Referring to FIG. 26, an etching process is applied to etch back thehard mask layer sufficiently so that the top surfaces of the patternedresist layer 330 are substantially exposed. The etch back process mayuse a CF4 dry etch, or a buffered hydrofluoric acid (BHF) wet etch toetch silicon dioxide. Some other proper etchants or processes may beutilized to achieve the etching back, such as chemical mechanicalpolishing (CMP) process.

Referring to FIG. 27, the patterned resist layer 330 is removed, forexample by a conventional process that can include wet stripping oroxygen plasma stripping. Thus, a reversed hard mask pattern is formed,in which the openings within the hard mask layer 340 are covered by thepatterned resist layer 330 before the removal of the resist layer 330.

At this point, the method can continue by etching the under layer 320through the openings in the hard mask layer 340, and then etching thesubstrate 310 using the under layer 320 as a mask. Alternatively,however, a procedure similar to that discussed above can be used to formanother reverse pattern, as will now be described. Referring to FIG. 28,another patterned resist layer 350 is formed on the patterned hard masklayer 340, and on the portions of the material layer 320 exposed withinthe openings of the hard mask layer 340. The resist layer 350 includes aplurality of openings that expose portions of the material layer 320.The patterned resist layer 350 may be substantially similar to theresist layer 330 discussed above, in terms of function, formation, andcomposition.

Referring to FIG. 29, another hard mask layer 360 is formed on thepatterned resist layer 350, and substantially fills the openings in thepatterned resist layer 350. The hard mask layer 360 substantially coversportions of the underlying material layer 320 that are exposed withinthe openings of the patterned resist layer 350. The hard mask layer 360includes a silicon-containing organic polymer, which may use a solventdifferent from that of the resist layer. The solvent of the hard masklayer is not capable of dissolving the resist layer 350. For example,the hard mask can use butanol, isobutanol, isopentanol and/or IPA as asolvent. The polymeric material may be cross-linked. The hard mask layer360 may include a silicon-containing inorganic polymer. For example, theinorganic polymeric material may include silicon oxide. The hard masklayer may alternatively include a metal-containing organic polymermaterial that contains a metal such as titanium, titanium nitride,aluminum, or tantalum. In another embodiment, the hard mask layer 360may include silicon nitride or silicon oxynitride. The hard mask layer360 may include pure silicon such as polycrystalline silicon or siliconoxide. For example, the hard mask layer 360 may include spin-on glass(SOG), known in the art. The hard mask layer 360 may be similar to thehard mask layer 340.

Referring to FIG. 30, an etching process is applied to etch back thehard mask layer 360 sufficiently so that the top surfaces of thepatterned resist layer 350 are substantially exposed. The etch backprocess may, for example, use a CF4 dry etch, or a buffered hydrofluoricacid (BHF) wet etch to etch silicon dioxide. Other proper process may beutilized to implement the etch back, such as chemical mechanicalpolishing (CMP).

Referring to FIG. 31, the patterned resist layer 350 is removed, forexample by a conventional process that includes wet stripping or oxygenplasma stripping. Thus, a reversed hard mask pattern is formed, in whichthe under layer 320 is exposed within the openings of the patterned hardmask layers 340 and 360.

The reversed hard mask pattern can be trimmed to reduce the widths ofthe hard mask islands, for realizing small feature sizes. In anotherexample, another resist layer may be applied and patterned such that atrimming process may be performed to modify the hard mask pattern withinparticular regions. For example, isolated trenches may be thus modifiedto eliminate an etching load effect. Such a reversed hard mask patterncan be incorporated into lithography patterning technologies. Forexample, the reversed hard mask pattern may be integrated withchromeless phase lithography. The chromeless phase lithography has highoptical contrast. The chromeless mask can print better images than PSMor a binary mask. For example, a chromeless mask can print an islandpattern by using a positive resist. The reverse hard mask pattern iscapable of transferring the island pattern to a hole pattern withimproved resolution. The method not only reverses the image pattern, butalso improves the etch resistance. A silicon-containing layer can beused as a hard mask in transferring the reversed pattern to the underlayer. The good etching selectivity of the silicon-containing layer withrespect to the under layer enables the under layer to have a high aspectratio. The under layer with a high thickness can achieve substratepatterning while eliminating pattern collapse and other issues. Thereversed hard mask pattern utilized with double patterning techniquescan be used in various applications. For example, if a line pattern canbe achieved with better quality through the reversed pattern with thedouble patterning technique, then various contact holes can be formedwith enhanced resolution.

Referring to FIG. 32, an etching process is applied to open theunderlying material layer 320 if it is formed on the substrate 310. Anetching process is chosen such that the underlying material layer 320has a higher etch rate relative to the etch rate of the hard mask layers340 and 360. For example, if the underlying material 320 includessilicon nitride, and the hard mask layers 340 and 360 include siliconoxide, a hot phosphoric acid (H3PO4) can be used to selectively removethe underlying material layer 320.

Referring to FIG. 33, another etching process is applied to etch thesubstrate 310 under the patterned underlying material layer 320. Thisetching process is chosen so that the substrate 310 is selectivelyetched. In one embodiment, the hard mask layer 340 and 360 is removedbefore the etching of the substrate 310. In another embodiment, the hardmask layer 340 and 360 may be removed along with the material layer 320after the etching of the substrate 310. In another embodiment, if thehard mask layer is directly disposed on the substrate 310, then theetching process is chosen so that the etchant has a higher etch rate forthe substrate 310 than for the hard mask layer 340 and 360. The underlayer 320 may be subsequently removed by an etching process, asillustrated in FIG. 34.

FIG. 35 is a flowchart of a method 400 for lithography patterning, wherethe method 400 implements the lithography patterning technique describedabove with respect to FIGS. 23-34. The method 400 begins at step 402 byforming an under material layer on a substrate, and then continues instep 404 by forming a first patterned resist layer on the underlyingmaterial layer. In step 406, a first hard mask layer is formed on thefirst patterned resist layer, and in step 408, the first hard mask layeris etched back to expose the top surfaces of the first patterned resistlayer. In step 410, the first patterned resist layer is removed. Themethod proceeds to step 412, where a second patterned resist layer isformed on the first patterned hard mask layer and on portions of theunderlying material layer exposed within the openings of the firstpatterned hard mask layer. In step 414, a second hard mask layer isformed on the second patterned resist layer. In step 416, the secondhard mask layer is etched back to expose the top surfaces of the secondpatterned resist layer, and then in step 418 the second patterned resistlayer is removed.

The method then proceeds to step 420, where the under material layerexposed within the openings of the hard mask layers is etched. Then instep 422, the substrate exposed within the openings of the undermaterial layer is etched. The hard mask layers, the patterned resistlayer, and the underlying material layer are removed, as described inassociation with FIGS. 23-34. As mentioned above, the under materiallayer may be alternatively avoided.

Various embodiments of a lithography patterning method and a top layermaterial have been introduced and described. Other modifications,variations, additions, and extensions may be used without departing fromthe scope of the disclosure. For example, a hardening process may beapplied to one resist layer using a plasma treatment, UV curing, ionimplantation, or e-beam treatment. A top layer, a middle layer, or anunder layer may be cross-linked (or cured) if necessary. In anotherexample, a resist layer and a silicon-containing (or metal-containing)material may use a different solvent to avoid mixing or interdiffusion.For example, a resist layer may use an organic solvent such as propyleneglycol monomethyl ether (PGME) or propylene glycol monomethyl etheracetate (PGMEA), while the top layer may use an alcohol solvent such asbutanol, isobutanol, pentanol, isopentanol and/or IPA. All of the abovetechniques that include hardening, cross-linking, and utilizingdifferent solvents may be alternatively implemented, or combined,depending on the configuration and the processing procedure.

Thus the present disclosure provides a method of lithography patterning.The method of lithography double patterning includes forming a firstmaterial layer on a substrate; forming a first patterned resist layerincluding at least one opening therein on the first material layer;forming a second material layer on the first patterned resist layer andthe first material layer; forming a second patterned resist layerincluding at least one opening therein on the second material layer; andetching the first and second material layers uncovered by the first andsecond patterned resist layers.

In the present method, the first and second material layers each mayinclude one of a silicon-containing material and a metal-containingmaterial. The first and second material layers each may include achemical unit selected from the group consisting of Si, Ti, TiN, Ta, Al,a metal ion, a metal complex, an organic metal, and combinationsthereof. The method may further include forming a third material on thesubstrate before the forming of the first material layer. The forming ofthe third material layer may include forming a polymeric materialselected from the group consisting of organic polymer, resist, BARC, andcombinations thereof. The method may further include etching the thirdmaterial layer uncovered by the first and second material layers afterthe etching of the first and second material layers. The method mayfurther include etching the substrate using the third material layer asa hard mask after the etching of the third material layer. The etchingof the third material layer may include using a plasma etchant selectedfrom the group consisting of oxygen plasma, nitrogen plasma, hydrogen,alkyl halide, and combinations thereof. The forming of the firstmaterial layer may include forming a material having a refractive indexranging between about 1.1 and 1.9, and an absorption value rangingbetween about 0.01 and 0.8. The forming of the patterned resist layermay include exposing the patterned resist layer utilizing a meansselected from a group consisting of a Krypton Fluoride (KrF) excimerlaser, an Argon Fluoride (ArF) excimer laser, extreme ultraviolet (EUV)technology, imprint technology, electron-beam technology, andcombinations thereof. The forming of each of the first and secondmaterial layers may include providing a cross-linking polymericmaterial. The providing of the cross-linking polymeric material mayinclude diffusing acid from the patterned resist layer to the secondmaterial layer or a baking process with a temperature in the rangebetween about 25° C. and 150° C. The forming of one of the first andsecond material layers may include utilizing a hardening process.

The present disclosure also provides another method of lithographypatterning. The method includes forming a first material layer on asubstrate; forming a first patterned resist layer including at least oneopening therein on the first material layer; forming a second materiallayer within the patterned resist layer, the second material layer beingdifferent from the first material layer; and removing the firstpatterned resist layer to form a pattern of the second material layerbeing complementary to the first patterned resist layer.

The disclosed method may further include opening the first materiallayer using the pattern of the second material layer as a mask, and mayfurther include etching the substrate within openings of the firstmaterial layer. The first material may be substantially free of siliconand the second material may contain silicon. The first material may besubstantially free of metal and the second material may contain metal.The second material layer may include a component selected from thegroup consisting of an organic polymer, an inorganic material, and asolvent system different from that of the first patterned resist layer.The second material may include cross-linkers. The method may furtherinclude cross-linking the second material by a thermal baking. Themethod may further include hardening the first patterned resist layerbefore the forming of the second material layer. The method may furtherinclude implementing an etch-back process to the second material layerbefore the removing of the first patterned resist layer. The method mayfurther include forming a second patterned resist layer including atleast one opening therein on the pattern of the second material and thesubstrate; forming a third material layer within the at least oneopening of the second patterned resist layer; and removing the secondpatterned resist layer to form a pattern of the third material beingcomplementary to the second patterned resist layer. The third materiallayer may be substantially similar to the first material layer. Themethod may further include opening the first material layer using thesecond and the third material layers as a mask. The forming of the firstmaterial layer may include forming a material having a refractive indexranging between about 1.1 and 1.9, and an absorption value rangingbetween about 0.001 and 0.8.

The present disclosure also provides another method including: forming afirst patterned resist layer including at least one opening therein on asubstrate; forming a first hard mask layer on the first patterned resistlayer; etching back the first hard mask layer to expose the firstpatterned resist layer; removing the first patterned resist layer;forming a second patterned resist layer including at least one openingtherein on the first hard mask layer and the substrate; forming a secondhard mask layer on the second patterned resist layer and the substrate;etching back the second hard mask layer to expose the second patternedresist layer; and removing the second patterned resist layer.

The disclosed method may further include etching the substrate uncoveredby the first and second hard mask layers. The etching back one of thefirst and second hard mask layers may include a process selected from adry etching, a wet etching, or a combination thereof. The first andsecond hard mask layers each may include at least one of Si, Ti, TiN,Al, and Ta. The forming of one of the first and second hard mask layersmay include forming a material selected from the group consisting ofsilicon, silicon oxide, silicon nitride, silicon oxynitride, andcombinations thereof. The forming one of the first and second hard masklayers may include forming a silicon-containing organic polymer. Theforming of the silicon-containing organic polymer may includecross-linking the silicon-containing organic polymer. The forming one ofthe first and second hard mask layers may include forming asilicon-containing inorganic polymer. The silicon-containing inorganicpolymer may include silicon oxide. The forming one of the first andsecond hard mask layers may include a process selected from spin-oncoating and chemical vapor deposition (CVD). The method may furtherinclude an etching process to trim the hard mask layer.

The present disclosure also provides a material utilized inphotolithography patterning. The material includes: a solvent consistingof one of isobutanol and isopentanol; and a first polymer that has afirst functional unit capable of enhancing etching resistance and atleast one of silicon and a metal.

The disclosed material may further include a cross-linker with aplurality of first reaction units. Each first reaction unit may includea functional group selected from the group consisting of OH, COOH,anhydride, and combinations thereof. The first polymer may furtherinclude a second reaction unit. The second reaction unit may include afunctional group selected from the group consisting of OH, COOH,anhydride, and combinations thereof. The material may further include asecond polymer having a second functional unit capable of absorbingimaging light. The second functional unit may include at least one of adouble bond, a triple bond, a tertiary carbon structure, andcombinations thereof. The second functional unit may include one of abenzyl group, a phenyl group, and combinations thereof. The secondpolymer may further include at least one of silicon and a metal. Thefirst and second polymers each may include a backbone unit selected fromthe group consisting of Si—O—Si, Si—Si, and combinations thereof. Thefirst and second polymers each may further include various unitsselected from the group consisting of hydrogen, halide, a straightalkyl, a branched alkyl, a cyclic alkyl, fluorinated alkyl, siliconcontain alkyl, silicon oxide contain alkyl, and combinations thereof,each being attached to the backbone unit. The first functional unit mayinclude at least one of a double bond, a triple bond, tertiary carbonstructure, and combinations thereof.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the detailed description thatfollows. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments disclosed herein. Thoseskilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A method of lithography patterning, comprising: forming a firstmaterial layer on a substrate; forming a first patterned resist layerincluding at least one opening therein on the first material layer;forming a second material layer within the at least one opening of thefirst patterned resist layer, the second material layer being differentfrom the first material layer; removing the first patterned resist layerto form a pattern of the second material layer being complementary tothe first patterned resist layer; forming a second patterned resistlayer including at least one opening therein on the pattern of thesecond material and the substrate; forming a third material layer withinthe at least one opening of the second patterned resist layer; andremoving the second patterned resist layer to form a pattern of thethird material, being complementary to the second patterned resistlayer.
 2. The method of claim 1, further comprising opening the firstmaterial layer using the pattern of the second material layer as a mask.3. The method of claim 2, further comprising etching the substratewithin openings of the first material layer.
 4. The method of claim 1,wherein the first material is substantially free of silicon and thesecond material contains silicon.
 5. The method of claim 1, wherein thefirst material is substantially free of metal and the second materialcontains metal.
 6. The method of claim 1, wherein the second materiallayer comprises a component selected from the group consisting oforganic polymer, inorganic material, and a solvent system different fromthat of the first patterned resist layer.
 7. The method of claim 1,wherein the second material comprises cross-linkers.
 8. The method ofclaim 1, further comprising implementing an etch-back process to thesecond material layer before the removing of the first patterned resistlayer.
 9. The method of claim 1, wherein the third material layer issubstantially similar to the first material layer.
 10. The method ofclaim 1, further comprising opening the first material layer using thesecond and the third material layers as a mask.
 11. A method,comprising: forming a first patterned resist layer including at leastone opening therein on a substrate; forming a first hard mask layer onthe first patterned resist layer and the substrate; etching back thefirst hard mask layer to expose the first patterned resist layer;removing the first patterned resist layer; forming a second patternedresist layer including at least one opening therein on the first hardmask layer and the substrate; forming a second hard mask layer on thesecond patterned resist layer and the substrate; etching back the secondhard mask layer to expose the second patterned resist layer; andremoving the second patterned resist layer.
 12. The method of claim 11,further comprising etching the substrate uncovered by the first andsecond hard mask layers.
 13. The method of claim 11, wherein the firstand second hard mask layers each includes at least one of Si, Ti, TiN,Al, and Ta.
 14. The method of claim 11, wherein forming one of the firstand second hard mask layers includes forming a material selected fromthe group consisting of silicon, silicon oxide, silicon nitride, siliconoxynitride, and combinations thereof
 15. The method of claim 11, whereinforming one of the first and second hard mask layers includes formingone of a silicon containing organic polymer and a silicon containinginorganic polymer.
 16. The method of claim 15, wherein the siliconcontaining inorganic polymer includes silicon oxide.
 17. The method ofclaim 11, further comprising an etching process to trim the hard masklayer.